Ferrier Rearrangement Of Tri-O-acetyl-D-glycals Catalyzed With H₂SO₄/4A MS And FeCl₃·6H₂O/C

Ferrier-type rearrangement is an important method for conversion of3,4,6-tri-O-acetyl-D-glycals to2,3-unsaturated-O-glycosides. The glycosides as chiral intermediates have played an important role in the synthesis of bioactive compounds, such as glycopeptides, oligosaccharides, uronic acids, antibiotics, and nucleosides. Recent years, there are many reports of the Ferrier rearrangement; however, drawbacks of the various catalysts, such as high cost, long reaction time, low yield and troublesome in post-processing are found in the reports. The thesis mainly reports using H2SO4/4A MS and FeCl3·6H2O/C as catalysts to catalyze the Ferrier-type reaction of3,4,6-tri-O-acetyl-D-glycals with a wide range of alcohols, phenols and sugurs.1) In this report, we have demonstrated a new, highly efficient synthesis of2,3-unsaturated-O-glycosides from3,4,6-tri-O-acetyl-D-glucals based on sulfuric acid/4A molecular sieves in CH2CI2at room temperature. The advantages of the present procedure are as follows:the method is simple, highly yielding (80～99%) and short reaction time (5min). The applied reagents, sulfuric acid and4A molecular sieves are easily available. Moreover, the efficient applicability of this methodology in scale-up conditions makes this idea more worthy for further research.2) Under the catalysis of solid acid FeCl3·6H2O/C,3,4,6-tri-O-acetyl-D-glucals and3,4,6-tri-O-acetyl-D-galactals can convert to2,3-unsaturated-O-glycosides via Ferrier-type rearrangement. This reaction is highly yielding with good to excellent selectivity and its applications are widespread to a variety of alcohols, phenols, thiophenols and sugur acceptors. In addition, this reaction can operate in scale-up conditions and the catalyst of solid acid FeCl3·6H2O/C can be repeatedly used even after two times.